Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel
Abstract
Laminar-turbulent transition is a pivotal factor for the design of hypersonic vehicles but the mechanisms that induce transition are not well understood. A laser differential interferometer (LDI) is a non-intrusive optical device that measures the optical path length difference between two laser beams. The LDI is a reliable calibrated instrument to assist the study of boundary layer instability-wave growth in hypersonic flow and has high sensitivity and frequency response. An LDI with a commercial balanced photodetector capable of detecting optical path length differences of lambda/21,000 from DC to 80 MHz was assembled and tested in the Purdue Quiet-Flow Ludwieg tube. Fluctuations in the subsonic region of a forward-facing cavity were measured with the LDI and compared to those detected with a Kulite pressure transducer at the base of the cavity. Predictions of self-resonating deep cavities were confirmed. The LDI was then adapted and transferred to the Boeing/AFOSR Mach-6 Quiet Tunnel.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 11, 2007
- Accession Number
- ADA474770
Entities
People
- Rodrigo Segura
Organizations
- Purdue University